|U.S. Department of Transportation|
|Federal Highway Administration|
|Subject::||INFORMATION: NCHRP Report 350 Nonproprietary Guardrails and Median Barriers||Date:|
|From:||Dwight A. Horne||
Resource Center Directors
In 1993, the FHWA formally adopted the performance evaluation guidelines for highway features set forth in the NCHRP Report 350. All new, permanent roadside and median barriers installed on the NHS must now meet these guidelines. Since one of the most significant changes in testing procedures was the substitution of a 2000-kg (4400-lb) pickup truck for the 4500-lb passenger sedan formerly used in crash-testing, testing was undertaken to re-certify existing hardware under the Report 350 guidelines.
Although the results of many of these re-certification tests were reported in the past and are generally known to Federal and State transportation agency personnel and others in the highway safety community, they have not been the subject of formal acceptance letters as is routinely done with proprietary and State-tested items at the manufacturer's or State's request. Consequently, this memorandum summarizes and describes all nonproprietary longitudinal roadside and median barriers that have met Report 350 requirements at one or more test levels or are considered equivalent to barriers that have been so tested. Where applicable, the reference page number for each barrier type included in the 1995 AASHTO-AGC-ARTBA "Guide to Standardized Highway Barrier Hardware" is noted in parenthesis. Some of these barriers have also been identified in earlier acceptance letters, but are included in this consolidated listing as well. In such instances, the original acceptance number is noted in parenthesis for ready reference.
* these two designs were tested as bridge railings. They may be used as roadside or median barriers if reinforcing and foundation details are equivalent to the crash tested installations.
** the Constant Slope Barriers were not tested to the TL-5 level, but may be considered TL-5 barriers when cast in place or slip formed if the dimensions, reinforcing, and foundation details are equivalent to designs that have been successfully tested.
Attachment 1 includes schematic drawings of most of the flexible and semi-rigid barriers listed above. Attachment 2 shows the dimensions of the routed wood block used with the strong steel post w-beam system. The block dimensions are the same for the routed Thrie-beam block, except that its length is 554 mm and it has two offset holes for bolting to the post flange. Additional information on blockouts for use with strong-post w-beam guardrail systems is contained in my January 27, 1998, memorandum to the field on that subject (Acceptance Letter B-44).
As additional nonproprietary barrier systems are tested, this acceptance letter will be supplemented accordingly. Any questions on this topic should be addressed to Mr. Richard Powers of my staff at (202) 366-1320.
cc:Reader - HMHS-1, Chron - Rm 3407
R. Powers - HMHS-10